1. Field of the Invention
The present invention relates to novel and useful amino alkane phosphonic acid compounds and more particularly to novel N-(hydroxy methyl) amino alkane phosphonic acids and their salts, to a process of producing such phosphonic acid compounds, to methods of using such compounds as stabilizing agents in perioxide-containing bleaching baths and especially to methods for bleaching cellulose fibers, either alone or in a blend with synthetic fibers, at a pH-value of at least 9.0, and to compositions containing such amino alkane phosphonic acid compounds.
2. Description of the Prior Art
N-(hydroxy alkyl) amino alkane-1,1-diphosphonic acids in which one or two hydrogen atoms at the nitrogen atoms are substituted by hydroxy alkyl groups of the formula C.sub.n H.sub.2n OH, in which formula n indicates the numerals 2 or 3, are disclosed in German Auslegeschrift No. 25 04 724. These compounds are obtained by reacting amino alkane diphosphonic acids with cyclic ethers having preferably two to three carbon atoms in their ring nucleus, at increased temperature. When proceeding according to this process, only N-(hydroxy ethyl) or, respectively, N-(hydroxy propyl) derivatives of amino alkane diphosphonic acids are obtained.
German Auslegeschrift No. 22 11 578 discloses the use of amino lower alkane polyphosphonates and/or hydroxy alkane phosphonates in mixture with hydroxy or polyhydroxy compounds having two to six carbon atoms in their carbon chain and, if desired, with poly-amino carboxylic acids, as stabilizing agents in bleaching baths. As has been demonstrated in the meantime, such combinations, used in place of silicates, have proved to have a very good stabilizing effect at higher temperatures and especially when bleaching is carried out according to the HT-process (high temperature process). These known stabilizing agents, however, do not yield satisfactory results when used for bleaching at low temperatures.
Furthermore, it is reported in the journal "Textilveredelung" Vol. 11 (1978), pages 159-160, in an article on "Investigations Regarding the Silicate-Free Stabilization of Peroxide-Containing Bleaching Liquors" that certain stabilizers yield satisfactory results. The composition of such stabilizers, however, is kept secret. Especially the stabilizer experiment mentioned in this report, is regarded as yielding satisfactory results, although, as is evident from the data given, a noticeable decrease of the DP-value from the initial value of 2,607 to a value of 2,373 is observed after a bleaching time of 24 hours.